I contacted Kiavi about it, since I never gave the client their contact and consent to contact my clients directly, and the account executive said, that since the borrower did not close with Kiavi on the previous loan I submitted to them, they basically have all rights to solicit your borrower's directly, and not pay you any referral fee or nor give you any heads up. 

Also, how to find out of states agents in contact with investors and good at finding off market deals?

I bet you will find a few posts of interest and people to contact.

The letter stated he was obligated to tender a defense for the buyers due to the statutory warranty deed and to contact the office immediately.We contacted an attorney on his behalf and he sent off a letter to try to figure out what next steps would be.

I am in contact with some lenders to explore options but they all seem to be a bit confused with me being not from the US.

Feel free to reach out via my contact info in my signature and I will share their contact info. 

My first stop would be to contact the Broker and follow up in writing that you will contact the real estate commission if this is not remedied within 10 days.  2nd stop would be a complaint with the Board of Realtors and the Real Estate Commission.  

Quote from @Yousef Hossam: After seeing how people work their pipelines, I realized something surprising:Many deals are lost after the seller already showed interest.Not from lack of leads, but from:Late repliesMissed follow-upsNotes scattered across toolsNo defined lead stagesNo accountability on daily pipeline actionsThe person who consistently close more usually have:One place where every conversation is loggedClear stages (New → Contacted → Follow-Up → Appointment → Contract)Automated or scheduled remindersA daily or weekly pipeline reviewNext steps always set before ending the callNothing fancy, just fundamentals done well.In many cases, tightening follow-up converts more deals without increasing marketing spend.Are you currently managing follow-up and pipeline visibility in your business?

It looks like it has been abandoned for some time (I am pretty sure the owners passed away).I have tried to contact the person paying the taxes on the property, but I have had no luck getting in contact with them. 

Once you determined that it can indeed help you, contact these BP experts, each one of them operates a reputable full-service cost segregation firm:  @Bernard Reisz, @Yonah Weiss, @Julio GonzalezThank you for the tag @Michael Plaks!